Introduce a SignatoryManager service. (#509)

* WIP: Introduce a SignatoryManager service.

The SignatoryManager manager provides an API to interact with keysets, private
keys, and all key-related operations, offering segregation between the mint and
the most sensible part of the mind: the private keys.

Although the default signatory runs in memory, it is completely isolated from
the rest of the system and can only be communicated through the interface
offered by the signatory manager. Only messages can be sent from the mintd to
the Signatory trait through the Signatory Manager.

This pull request sets the foundation for eventually being able to run the
Signatory and all the key-related operations in a separate service, possibly in
a foreign service, to offload risks, as described in #476.

The Signatory manager is concurrent and deferred any mechanism needed to handle
concurrency to the Signatory trait.

* Fixed missing default feature for signatory

* Do not read keys from the DB

* Removed KeysDatabase Trait from MintDatabase

All Keys operations should be done through the signatory

* Make sure signatory has all the keys in memory

Drop also foreign constraints on sqlite

* Fix race condition

* Adding debug info to failing test

* Add `sleep` in test

* Fixed issue with active auth keyset

* Fixed dependency

* Move all keys and keysets to an ArcSwap.

Since the keys and keysets exist in RAM, most wrapping functions are infallible
and synchronous, improving performance and adding breaking API changes.

The signatory will provide this information on the boot and update when the
`rotate_keyset` is executed.

Todo: Implement a subscription key to reload the keys when the GRPC server
changes the keys. For the embedded mode, that makes no sense since there is a
single way to rotate keys, and that bit is already covered.

* Implementing https://github.com/cashubtc/nuts/pull/250

* Add CLI for cdk-signatory to spawn an external signatory

Add to the pipeline the external signatory

* Update tests

* Apply suggestions from code review

Co-authored-by: ok300 <106775972+ok300@users.noreply.github.com>
Co-authored-by: thesimplekid <tsk@thesimplekid.com>

* Minor change

* Update proto buf to use the newest format

* Rename binary

* Add instrumentations

* Add more comments

* Use a single database for the signatory

Store all keys, even auth keys, in a single database. Leave the MintAuthDatabse
trait implementation for the CDK but not the signagtory

This commit also moves the cli mod to its own file

* Update dep

* Add `test_mint_keyset_gen` test

---------

Co-authored-by: ok300 <106775972+ok300@users.noreply.github.com>
Co-authored-by: thesimplekid <tsk@thesimplekid.com>

misc/fake_itests.sh

@@ -7,13 +7,15 @@ cleanup() {
     echo "Killing the cdk mintd"
     kill -2 $CDK_MINTD_PID
     wait $CDK_MINTD_PID
+    kill -9 $CDK_SIGNATORY_PID
+    wait $CDK_SIGNATORY_PID
 
     echo "Mint binary terminated"
-    
+
     # Remove the temporary directory
     rm -rf "$CDK_ITESTS_DIR"
     echo "Temp directory removed: $CDK_ITESTS_DIR"
-    
+
     # Unset all environment variables
     unset CDK_ITESTS_DIR
     unset CDK_ITESTS_MINT_ADDR
@@ -49,7 +51,7 @@ fi
 echo "Temp directory created: $CDK_ITESTS_DIR"
 export CDK_MINTD_DATABASE="$1"
 
-cargo build -p cdk-integration-tests 
+cargo build -p cdk-integration-tests
 
 
 export CDK_MINTD_URL="http://$CDK_ITESTS_MINT_ADDR:$CDK_ITESTS_MINT_PORT"
@@ -62,6 +64,14 @@ export CDK_MINTD_MNEMONIC="eye survey guilt napkin crystal cup whisper salt lugg
 export CDK_MINTD_FAKE_WALLET_FEE_PERCENT="0"
 export CDK_MINTD_FAKE_WALLET_RESERVE_FEE_MIN="1"
 
+if [ "$2" = "external_signatory" ]; then
+    export CDK_MINTD_SIGNATORY_URL="https://127.0.0.1:15060"
+    export CDK_MINTD_SIGNATORY_CERTS="$CDK_ITESTS_DIR"
+    bash -x `dirname $0`/../crates/cdk-signatory/generate_certs.sh $CDK_ITESTS_DIR
+    cargo run --bin signatory -- -w $CDK_ITESTS_DIR -u "sat" -u "usd"  &
+    export CDK_SIGNATORY_PID=$!
+    sleep 5
+fi
 
 echo "Starting fake mintd"
 cargo run --bin cdk-mintd --features "redb" &
@@ -74,7 +84,7 @@ START_TIME=$(date +%s)
 while true; do
     # Get the current time
     CURRENT_TIME=$(date +%s)
-    
+
     # Calculate the elapsed time
     ELAPSED_TIME=$((CURRENT_TIME - START_TIME))